There exist numerous devices which require a high precision manufacturing method, such as, for example, in micro technical fields like horology. Indeed, the world of horology works with dimensions that range from a millimeter to a tenth of a millimeter. Gear trains or escapements are among the examples of devices where precision is important. The escapement is formed of a pallet lever and an escape wheel cooperating with each other, the rotation of the escape wheel being regulated by the pallet lever of the escape system whose impulses are supplied by a sprung balance. The impulses are therefore important. These impulses are achieved by pallet stones which are inserted in the pallet lever and come into contact with the escape wheel. If the pallet stones of the lever are not properly positioned, the impulses between the pallet stones of the lever and the escape wheel are not perfect and losses occur which affect the efficiency of the escapement and therefore the accuracy and autonomy of the watch.
Currently, pallet stones are assembled on a pallet lever using shellac, which is a natural product with the properties of thermoplastics. Viscosity is difficult to control with this type of material and it is difficult to control the volume of adhesive deposited. It therefore often happens that the shellac overflows which causes aesthetic defects which may be unacceptable. Further, the shellac is an organic material which is subject to ageing and consequently the pallet stone setting may be weakened over time.
Another possibility is to use brazing or welding. However, these two solutions are also problematic since, to successfully weld a ceramic or silicon or mineral material, reactive brazing/welding has to be used, which must be performed at a relatively high temperature (generally above 700° C.) and in a neutral or high vacuum atmosphere. This results in very long assembly cycles and breaks and cracks may appear in the material.
There also exist devices which require not only a high level of precision, but also a manufacturing method which is gentle on the component parts. Silicon, which is an increasingly used material, particularly in horology, can be cited here in particular. This material, which has no usable plastic range, is used to make gear wheels or escape system pallet levers, but has the drawback of being very fragile. Currently, no method other than bonding exists for securing a silicon wheel to an arbour. Bonding has the drawbacks of being difficult to reproduce, of generating organic compounds which may degrade the oils used and of weakening over time.